Abstract

We demonstrate very-long-wavelength infrared type II superlatticephotodiodes with a cutoff wavelength of . We observed a zero-bias, peak Johnson noise-limited detectivity of at 77 K with a 90%–10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product measurements indicated that silicon dioxide passivation increased surfaceresistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall uniformity. The bulk at 77 K was found to be , with increasing more than twofold at 25 mV reverse bias.